The present disclosure relates to a sheet feeding device preferably applied in a copying machine, a printer or the like and to an image forming apparatus including this.
There is a sheet (document) feeding device feeding a document placed on a feeding tray to an image reading part by a conveying device and ejecting the document after the completion of reading in the image reading part to an ejected sheet tray positioned below the feeding tray.
For example, there is an automatic sheet feeding device including a document guide slidably operated in accordance with width of the document placed on a document platen to regulate ends in a width direction of the document and three sensors detecting a slide position of the document guide. In this automatic sheet feeding device, each sensor detects size of the document on the document platen on the basis of the position of the document guide. The document after conveying process and reading process from the document platen is ejected below the document platen.
Moreover, for example, there is an automatic sheet feeding device including a feeding sheet tray and an ejected sheet tray. The feeding sheet tray has a pair of left and right feeding sheet side guide plates opposed to each other slidably in a document width direction. The ejected sheet tray has a pair of left and right ejected sheet side guide plates respectively integrated with the feeding sheet side guide plates and configured to be slidable in interlocking with the feeding sheet side guide plates. The ejected sheet tray is also arranged below the feeding sheet tray. In this automatic sheet feeding device, a conveying part leads the document on the feeding sheet tray to an image reading part. The document after the reading process is ejected to the ejected sheet tray.
Incidentally, the above-mentioned former and latter automatic sheet feeding devices convey a plurality of the documents in order and carry out the reading process. The plurality of the ejected documents are placed on the ejected sheet tray in a stacked state. Such automatic sheet feeding devices generally feed the ejected document obliquely upward to the ejected sheet tray in order to prevent paper jam, incorrect collation and others from causing by a collision of the following ejected document with the document already ejected on the ejected sheet tray.
However, because the document ejected obliquely upward collides a lower face of the feeding sheet tray and is not placed at an appropriate position on the ejected sheet tray, there is a possibility that such a document causes the jam, incorrect collation and others in the vicinity of a sheet ejected port. In general, in the above-mentioned automatic sheet feeding devices, a plurality of conveying ribs changing an ejecting direction to a lower direction are fixedly arranged in the vicinity of an ejecting port of the document (e.g. in the lower face of the feeding sheet tray and others). The document is placed at the appropriate position on the ejected sheet tray by the plurality of conveying ribs. Because contact area of the ejected document surface with the conveying rib is reduced, the document is smoothly ejected.
However, it is necessary to position the conveying ribs at appropriate positions corresponding with the size of the document. In the above-mentioned automatic sheet feeding devices, it is necessary to arrange the plurality of the conveying ribs in the width direction of the document in parallel in order to correspond with the documents of different sizes. Therefore, the above-mentioned automatic sheet feeding devices have a problem that, as the size of the document is increased, the number of the conveying ribs to be installed is increased. If one sized document is fitted to a side face of the conveying ribs corresponding with another sized document, the ejection of the one document may be interfered (an occurrence of ejection interference).